Democrat Julian Castro promised a 9-year-old girl in Urbandale who asked him about climate change that his first executive order as president would be to sign the Paris Climate Accord. That, Castro said during an Urbandale house party on Friday, would ensure her generation has cleaner air and water.

Castro called climate change “the biggest threat we face in this country” and told the girl if it’s not fixed soon, “it may be that one day there is no United States of America.”

Scarlett Montgomery, who’s going into the fourth grade, said she asked the question about climate change because “it’s bad for the planet and people can’t really live with it for long.”

She’s been out listening to other candidates on the issue as well. So far, she’s also seen Beto O’Rourke and Eric Swalwell speak. Castro was her favorite speaker as of Friday evening.

Castro, who spent time earlier in the day talking to Waukee residents who have seen rent hikes in recent months about affordable housing, answered questions from about 40 people gathered in Urbandale for nearly an hour.

One of the questions Castro said he gets asked most is what he’ll do if he’s elected president, but Mitch McConnell is still serving in the U.S. Senate. McConnell will likely block everything a Democratic president tries to do, Castro noted.

To override McConnell, Castro said he would “maximize every executive authority in every way that we could.”

He said he’d also work to appoint as many judges to the federal bench as he could, adding, “I am going to going to put an emphasis on appointing judges that are progressive.”

There has been an all-out assault on a woman’s right to choose, Castro said. He then said he’d get rid of the Hyde Amendment because “it doesn’t matter if a woman is poor or if she’s wealthy, she should enjoy the same constitutional right.”

Castro was fresh out of his town hall meeting with Fox News Friday, and he defended his decision to appear on the controversial network.

“I hope for those of you all who had a chance to watch noticed that I stood up for our progressive values and I did not back down one inch on any of the questions,” Castro said. “Whether it was about a woman’s right to have an abortion in this country, or on the issue of immigration and using common sense and compassion — instead of cruelty like the President has — or on an issue like police accountability. And I’m going to continue to do that.”